Spinal muscular atrophy, Ryukyuan type: A recessively inherited disorder occurring in males from a Japanese inhabitants of Ryukyu Islands. The disorder is characterized by muscle wasting and weakness that affects the lower legs more than the arms.
Leg weakness Leg wasting Arm weakness Arm wasting Scoliosis
Weakness is most severe in muscles closest to the center of the body, such as those of the shoulders, hips, thighs and upper back. Respiratory muscle weakness and spinal curvature sometimes develop.